When I cheked AOA values from ALPHA CALL UP A 330-300, I had seen those approximate angle values at 3 degree final approach at Vref+5 or Vls+5. Here, Weight is not a factor because it increases Vref or Vls
CONF FULL: 6 degree (at Vref+5)
CONF 3 7.5 degree (at Vls)
The above angle values are big enough for stall at high altitude (high mach No). When cruising at high altitude, approximate AOA is 2.5-3.0 degrees. To trigger stall warning for slightly greater angles than 3.0 degree, ADC can bias mach Effect for this measured AOA PROBE/VANE values at high altitude.
Also, since the accuracy of AOA PROBE measurements decreases due to compressibility effect, when mathematical model of this error is set, accuracy of AOA can also be maintained at high Mach number.
These all sounds nice but as seen, only possible if Mach Number is calculated.. In case of UAS, the corret Mach number cannot be known for all above corrections. This means a kind of vicious Circle; in another word, if Speed/Mach cannot be measured correctly then AOA measurement cannot be corrected for use at high Mach Number. Means AOA measurement can not be independent from correct mach measurement at high mach number.
Boeing Aero Magazine Issue 12 (I am sure it can be downloaded in web) explains all details about AOA measurement and pros/ cons when displayed in cockpit. It explains why AOA display sometimes becomes useless; similiar to I have tried to explain with my poor English above